Control system for a dual clutch transmission

ABSTRACT

A hydraulic control system for a dual clutch transmission includes a plurality of pressure and flow control devices and logic valve assemblies in fluid communication with a plurality of clutch actuators and with a plurality of synchronizer actuators. The clutch actuators are operable to actuate a plurality of torque transmitting devices and the synchronizer actuators are operable to actuate a plurality of synchronizer assemblies. Selective activation of combinations of the pressure control solenoids and the flow control solenoids allows for a pressurized fluid to activate at least one of the clutch actuators and synchronizer actuators in order to shift the transmission into a desired gear ratio.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/285,483, filed on Dec. 10, 2009, which is hereby incorporated in itsentirety herein by reference.

TECHNICAL FIELD

The invention relates to a control system for a dual clutchtransmission, and more particularly to an electro-hydraulic controlsystem having a plurality of solenoids and valves operable to actuate aplurality of actuators within the dual clutch transmission.

BACKGROUND

A typical multi-speed, dual clutch transmission uses a combination oftwo friction clutches and several dog clutch/synchronizers to achieve“power-on” or dynamic shifts by alternating between one friction clutchand the other, with the synchronizers being “pre-selected” for theoncoming ratio prior to actually making the dynamic shift. “Power-on”shifting means that torque flow from the engine need not be interruptedprior to making the shift. This concept typically uses countershaftgears with a different, dedicated gear pair or set to achieve eachforward speed ratio. Typically an electronically controlled hydrauliccontrol circuit or system is employed to control solenoids and valveassemblies. The solenoid and valve assemblies actuate clutches andsynchronizers to achieve the forward and reverse gear ratios.

While previous hydraulic control systems are useful for their intendedpurpose, the need for new and improved hydraulic control systemconfigurations within transmissions which exhibit improved performance,especially from the standpoints of efficiency, responsiveness andsmoothness, is essentially constant. Accordingly, there is a need for animproved, cost-effective hydraulic control system for use in a dualclutch transmission.

SUMMARY

A hydraulic control system for a dual clutch transmission includes aplurality of pressure and flow control devices and logic valves in fluidcommunication with a plurality of clutch actuators and with a pluralityof synchronizer actuators. The clutch actuators are operable to actuatea plurality of torque transmitting devices and the synchronizeractuators are operable to actuate a plurality of synchronizerassemblies. Selective activation of combinations of the pressure controlsolenoids and the flow control solenoids allows for a pressurized fluidto activate at least one of the clutch actuators and synchronizeractuators in order to shift the transmission into a desired gear ratio.

In one example of the hydraulic control system, the hydraulic controlsystem includes an electric pump and an accumulator that provide apressurized hydraulic fluid.

In another example of the hydraulic control system, the hydrauliccontrol system includes two pressure control devices and two flowcontrol devices used to actuate the dual clutch.

In yet another example of the hydraulic control system, the hydrauliccontrol system includes two pressure control devices, two flow controldevices, and two logic valves used to actuate the plurality ofsynchronizer assemblies.

Further features, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a schematic diagram of an exemplary dual clutch transmissionhaving a hydraulic control system according to the principles of thepresent invention; and

FIGS. 2A-B are schematic diagrams of an embodiment of a hydrauliccontrol system for a dual clutch transmission according to theprinciples of the present invention.

DESCRIPTION

With reference to FIG. 1, an exemplary dual clutch automatictransmission incorporating the present invention is illustrated andgenerally designated by the reference number 10. The dual clutchtransmission 10 includes a typically cast, metal housing 12 whichencloses and protects the various components of the transmission 10. Thehousing 12 includes a variety of apertures, passageways, shoulders andflanges which position and support these components. While the housing12 is illustrated as a typical rear wheel drive transmission, it shouldbe appreciated that the transmission 10 may be a front wheel drivetransmission or a rear wheel drive transmission without departing fromthe scope of the present invention. The transmission 10 includes aninput shaft 14, an output shaft 16, a dual clutch assembly 18, and agear arrangement 20. The input shaft 14 is connected with a prime mover(not shown) such as an internal combustion gas or Diesel engine or ahybrid power plant. The input shaft 14 receives input torque or powerfrom the prime mover. The output shaft 16 is preferably connected with afinal drive unit (not shown) which may include, for example, propshafts,differential assemblies, and drive axles. The input shaft 14 is coupledto and drives the dual clutch assembly 18. The dual clutch assembly 18preferably includes a pair of selectively engageable torque transmittingdevices including a first torque transmitting device 22 and a secondtorque transmitting device 24. The torque transmitting devices 22, 24are preferably dry clutches. The torque transmitting devices 22, 24 aremutually exclusively engaged to provide drive torque to the geararrangement 20.

The gear arrangement 20 includes a plurality of gear sets, indicatedgenerally by reference number 26, and a plurality of shafts, indicatedgenerally by reference number 28. The plurality of gear sets 26 includesindividual intermeshing gears that are connected to or selectivelyconnectable to the plurality of shafts 28. The plurality of shafts 28may include layshafts, countershafts, sleeve and center shafts, reverseor idle shafts, or combinations thereof. It should be appreciated thatthe specific arrangement and number of the gear sets 26 and the specificarrangement and number of the shafts 28 within the transmission 10 mayvary without departing from the scope of the present invention. In theexample provided, the transmission 10 provides seven forward gears and areverse gear.

The gear arrangement 20 further includes a first synchronizer assembly30A, a second synchronizer assembly 30B, a third synchronizer assembly30C, and a fourth synchronizer assembly 30D. The synchronizer assemblies30A-D are operable to selectively couple individual gears within theplurality of gear sets 26 to the plurality of shafts 28. Eachsynchronizer assembly 30A-D is disposed either adjacent certain singlegears or between adjacent pairs of gears within adjacent gear sets 26.Each synchronizer assembly 30A-D, when activated, synchronizes the speedof a gear to that of a shaft and a positive clutch, such as a dog orface clutch. The clutch positively connects or couples the gear to theshaft. The clutch is bi-directionally translated by a shift rail andfork assembly (not shown) within each synchronizer assembly 30A-D.

The transmission also includes a transmission control module 32. Thetransmission control module 32 is preferably an electronic controldevice having a preprogrammed digital computer or processor, controllogic, memory used to store data, and at least one I/O peripheral. Thecontrol logic includes a plurality of logic routines for monitoring,manipulating, and generating data. The transmission control module 32controls the actuation of the dual clutch assembly 18 and thesynchronizer assemblies 30A-D via a hydraulic control system 100according to the principles of the present invention.

Turning to FIGS. 2A-B, the hydraulic control system 100 of the presentinvention is operable to selectively engage the dual clutch assembly 18and the synchronizer assemblies 30A-D by selectively communicating ahydraulic fluid 102 from a sump 104 to a plurality of shift actuatingdevices, as will be described in greater detail below. The sump 104 is atank or reservoir preferably disposed at the bottom of the transmissionhousing 12 to which the hydraulic fluid 104 returns and collects fromvarious components and regions of the automatic transmission 10. Thehydraulic fluid 102 is forced from the sump 104 via a pump 106. The pump106 is preferably driven by an electric engine (not shown) or any othertype of prime mover and may be, for example, a gear pump, a vane pump, agerotor pump, or any other positive displacement pump. The pump 106includes an inlet port 108 and an outlet port 110. The inlet port 108communicates with the sump 104 via a suction line 112. The outlet port110 communicates pressurized hydraulic fluid 102 to a supply line 114.The supply line 114 is in communication with a spring biased blow-offsafety valve 116, a pressure side filter 118, and a spring biased checkvalve 120. The spring biased blow-off safety valve 116 communicates withthe sump 104. The spring biased blow-off safety valve 116 is set at arelatively high predetermined pressure and if the pressure of thehydraulic fluid 102 in the supply line 114 exceeds this pressure, thesafety valve 116 opens momentarily to relieve and reduce the pressure ofthe hydraulic fluid 102. The pressure side filter 118 is disposed inparallel with the spring biased check valve 120. If the pressure sidefilter 118 becomes blocked or partially blocked, pressure within supplyline 114 increases and opens the spring biased check valve 120 in orderto allow the hydraulic fluid 102 to bypass the pressure side filter 118.

The pressure side filter 118 and the spring biased check valve 120 eachcommunicate with an outlet line 122. The outlet line 122 is incommunication with a second check valve 124. The second check valve 124is in communication with a main supply line 126 and is configured tomaintain hydraulic pressure within the main supply line 126. The mainsupply line 126 supplies pressurized hydraulic fluid to an accumulator130 and a main pressure sensor 132. The accumulator 130 is an energystorage device in which the non-compressible hydraulic fluid 102 is heldunder pressure by an external source. In the example provided, theaccumulator 130 is a spring type or gas filled type accumulator having aspring or compressible gas that provides a compressive force on thehydraulic fluid 102 within the accumulator 130. However, it should beappreciated that the accumulator 130 may be of other types, such as agas-charged type, without departing from the scope of the presentinvention. Accordingly, the accumulator 130 is operable to supplypressurized hydraulic fluid 102 back to the main supply line 126.However, upon discharge of the accumulator 130, the second check valve124 prevents the pressurized hydraulic fluid 102 from returning to thepump 106. The accumulator 130, when charged, effectively replaces thepump 106 as the source of pressurized hydraulic fluid 102, therebyeliminating the need for the pump 106 to run continuously. The mainpressure sensor 132 reads the pressure of the hydraulic fluid 102 withinthe main supply line 126 in real time and provides this data to thetransmission control module 32.

The main supply line 126 is channeled through a heat sink 134 used tocool the controller 32, though it should be appreciated that the heatsink 134 may be located elsewhere or removed from the hydraulic controlsystem 100 without departing from the scope of the present invention.The main supply line 126 supplies pressurized hydraulic fluid 102 tofour pressure control devices including a first clutch pressure controldevice 136, a second clutch pressure control device 138, and a firstactuator pressure control device 140, and a second actuator pressurecontrol device 141.

The first clutch pressure control device 136 is preferably anelectrically controlled variable force solenoid having an internalclosed loop pressure control. Various makes, types, and models ofsolenoids may be employed with the present invention so long as thefirst clutch pressure control device 136 is operable to control thepressure of the hydraulic fluid 102. The first clutch pressure controldevice 136 includes an inlet port 136A that communicates with an outletport 136B when the first clutch pressure control device 136 is activatedor energized and includes an exhaust port 136C that communicates withthe outlet port 136B when the first clutch pressure control device 136is inactive or de-energized. Variable activation of the first clutchpressure control device 136 regulates or controls the pressure of thehydraulic fluid 102 as the hydraulic fluid 102 communicates from theinlet port 136A to the outlet port 136B. The internal closed looppressure control provides pressure feedback within the solenoid toadjust the amount of flow to the outlet port 1368 based on a particularcurrent command from the controller 32, thereby controlling pressure.The inlet port 136A is in communication with the main supply line 126.The outlet port 136B is in communication with an intermediate line 142.The exhaust port 136C is in communication with the sump 104.

The intermediate line 142 communicates the hydraulic fluid 102 from thefirst clutch pressure control device 136 to a first clutch flow controldevice 144, to a first pressure limit control valve 146, and a three wayball check valve 147. The first clutch flow control device 144 ispreferably an electrically controlled variable force solenoid that isoperable to control a flow of the hydraulic fluid 102 from the firstclutch flow control device 144 in order to actuate the first torquetransmitting device 22, as will be described in greater detail below.The first clutch flow control device 144 includes an inlet port 144Athat communicates with an outlet port 144B when the first clutch flowcontrol device 144 is activated or energized and includes an exhaustport 144C that communicates with the outlet port 144B when the firstclutch flow control device 144 is inactive or de-energized. Variableactivation of the first clutch flow control device 144 regulates orcontrols the flow of the hydraulic fluid 102 as the hydraulic fluid 102communicates from the inlet port 144A to the outlet port 144B. The inletport 144A is in communication with the intermediate line 142. The outletport 144B is in communication with a first clutch supply line 148 and aflow restriction orifice 150. The exhaust port 144C is in communicationwith the sump 104. The first pressure limit control valve 146 isdisposed in parallel with the first clutch flow control solenoid 144 andis in communication with the first clutch supply line 148. If pressurewithin the first clutch supply line 148 exceeds a predetermined value,the first pressure limit control valve 146 opens to relieve and reducethe pressure.

The first clutch supply line 148 is in fluid communication with aninlet/outlet port 152A in a first clutch piston assembly 152. The firstclutch piston assembly 152 includes a single acting piston 154 slidablydisposed in a cylinder 156. The piston 154 translates under hydraulicpressure to engage the first torque transmitting device 22, shown inFIG. 1. When the first clutch flow control device 144 is activated orenergized, a flow of pressurized hydraulic fluid 102 is provided to thefirst clutch supply line 148. The flow of pressurized hydraulic fluid102 is communicated from the first clutch supply line 148 to the firstclutch piston assembly 152 where the pressurized hydraulic fluid 102translates the piston 154, thereby engaging the first torquetransmitting device 22. When the first clutch flow control solenoid 144is de-energized, the inlet port 144A is closed and hydraulic fluid fromthe cylinder 156 passes from the outlet port 144B to the exhaust port144C and into the sump 104, thereby disengaging the first torquetransmitting device 22.

The second clutch pressure control device 138 is preferably anelectrically controlled variable force solenoid having an internalclosed loop pressure control. Various makes, types, and models ofsolenoids may be employed with the present invention so long as thesecond clutch pressure control device 138 is operable to control thepressure of the hydraulic fluid 102. The second clutch pressure controldevice 138 includes an inlet port 138A that communicates with an outletport 138B when the second clutch pressure control device 138 isactivated or energized and includes an exhaust port 138C thatcommunicates with the outlet port 138B when the second clutch pressurecontrol device 138 is inactive or de-energized. Variable activation ofthe second clutch pressure control device 138 regulates or controls thepressure of the hydraulic fluid 102 as the hydraulic fluid 102communicates from the inlet port 138A to the outlet port 138B. Theinternal closed loop pressure control provides pressure feedback withinthe solenoid to adjust the amount of flow to the outlet port 1388 basedon a particular current command from the controller 32, therebycontrolling pressure. The inlet port 138A is in communication with themain supply line 126. The outlet port 138B is in communication with anintermediate line 158. The exhaust port 138C is in communication withthe sump 104.

The intermediate line 158 communicates the hydraulic fluid 102 from thesecond clutch pressure control device 138 to a second clutch flowcontrol device 160, to a second pressure limit control valve 162, and tothe three-way ball check valve 147. The second clutch flow controldevice 160 is preferably an electrically controlled variable forcesolenoid that is operable to control a flow of the hydraulic fluid 102from the second clutch flow control device 160 in order to actuate thesecond torque transmitting device 24, as will be described in greaterdetail below. The second clutch flow control device 160 includes aninlet port 160A that communicates with an outlet port 160B when thesecond clutch flow control device 160 is activated or energized andincludes an exhaust port 160C that communicates with the outlet port160B when the second clutch flow control device 160 is inactive orde-energized. Variable activation of the second clutch flow controldevice 160 regulates or controls the flow of the hydraulic fluid 102 asthe hydraulic fluid 102 communicates from the inlet port 160A to theoutlet port 160B. The inlet port 160A is in communication with theintermediate line 158. The outlet port 160B is in communication with asecond clutch supply line 164 and a flow restriction orifice 166. Theexhaust port 160C is in communication with the sump 104. The secondpressure limit control valve 162 is disposed in parallel with the secondclutch flow control solenoid 160 and is in communication with the secondclutch supply line 164. If pressure within the second clutch supply line164 exceeds a predetermined value, the second pressure limit controlvalve 162 opens to relieve and reduce the pressure.

The second clutch supply line 164 is in fluid communication with aninlet/outlet port 168A in a second clutch piston assembly 168. Thesecond clutch piston assembly 168 includes a single acting piston 170slidably disposed in a cylinder 172. The piston 170 translates underhydraulic pressure to engage the second torque transmitting device 24,shown in FIG. 1. When the second clutch flow control device 160 isactivated or energized, a flow of pressurized hydraulic fluid 102 isprovided to the second clutch supply line 166. The flow of pressurizedhydraulic fluid 102 is communicated from the second clutch supply line166 to the second clutch piston assembly 168 where the pressurizedhydraulic fluid 102 translates the piston 170, thereby engaging thesecond torque transmitting device 24. When the second clutch flowcontrol solenoid 160 is de-energized, the inlet port 160A is closed andhydraulic fluid from the cylinder 172 passes from the outlet port 160Bto the exhaust port 160C and into the sump 104, thereby disengaging thesecond torque transmitting device 24.

The three-way ball check valve 147 includes three ports 147A, 147B, and147C. The ball check valve 147 closes off whichever of the ports 147Aand 147B that is delivering the lower hydraulic pressure and providescommunication between whichever of the ports 147A and 147B having ordelivering the higher hydraulic pressure with the outlet port 147C. Theports 147A and 147B each communicate with the pressure control devices136 and 138, respectively. The outlet port 147C is in communication witha control device feed line 173. The control device feed line 173communicates with a valve control device 174. Accordingly, activation ofeither clutch pressure control devices 136 and 138 provides a flow ofpressurized hydraulic fluid 102 to the valve control device 174 via thecontrol device feed line 173 without allowing a flow of pressurizedhydraulic fluid 102 into the circuit of the inactivated clutch pressurecontrol device 136, 138.

The first and second pressure control devices 140 and 141 are operableto selectively provide flows of pressurized hydraulic fluid 102 throughfirst and second flow control devices 178, 180 and through first andsecond valve assemblies 182, 184 in order to selectively actuate aplurality of synchronizer shift actuators. The synchronizer actuatorsinclude a first synchronizer actuator 186A, a second synchronizeractuator 186B, a third synchronizer actuator 186C, and a fourthsynchronizer actuator 186D.

For example, the first actuator pressure control device 140 ispreferably an electrically controlled variable force solenoid having aninternal closed loop pressure control. Various makes, types, and modelsof solenoids may be employed with the present invention so long as thefirst actuator pressure control device 140 is operable to control thepressure of the hydraulic fluid 102. The first actuator pressure controldevice 140 includes an inlet port 140A that communicates with an outletport 140B when the first actuator pressure control device 140 isactivated or energized and includes an exhaust port 140C thatcommunicates with the outlet port 140B when the first actuator pressurecontrol device 140 is inactive or de-energized. Variable activation ofthe first actuator pressure control device 140 regulates or controls thepressure of the hydraulic fluid 102 as the hydraulic fluid 102communicates from the inlet port 140A to the outlet port 140B. Theinternal closed loop pressure control provides pressure feedback withinthe solenoid to adjust the amount of flow to the outlet port 140B basedon a particular current command from the controller 32, therebycontrolling pressure. The inlet port 140A is in communication with themain supply line 126. The outlet port 140B is in communication with anintermediate line 188. The exhaust port 140C is in communication withthe sump 104.

The intermediate line 188 communicates pressurized hydraulic fluid 102from the first actuator pressure control device 140 to a first flowcontrol device 178 and the first valve assembly 182. The first flowcontrol device 178 is preferably an electrically controlled variableforce solenoid. Various makes, types, and models of solenoids may beemployed with the present invention so long as the first flow controldevice 178 is operable to control the flow of the hydraulic fluid 102.The first flow control device 178 includes an inlet port 178A thatcommunicates through an adjustable hydraulic orifice or restriction withan outlet port 178B when the first flow control device 178 is activatedor energized and includes an exhaust port 178C that communicates withthe outlet port 178B when the first flow control device 178 is inactiveor de-energized. Variable activation of the first flow control device178 regulates or controls the flow of the hydraulic fluid 102 as thehydraulic fluid 102 communicates from the inlet port 178A to the outletport 178B. The inlet port 178A is in communication with the intermediateline 188. The outlet port 178B is in communication with an intermediateline 190 which communicates with the first valve assembly 182. Theexhaust port 178C is in communication with the sump 104.

The first valve assembly 182 is operable to selectively direct thepressurized hydraulic fluid 102 flows from the first pressure controldevice 140 and the first actuator flow control device 178 to the firstsynchronizer actuator 186A and to the second synchronizer actuator 186B,as will be described in greater detail below. The first valve assembly182 includes a first inlet port 182A, a second inlet port 182B, a firstoutlet port 182C, a second outlet port 182D, a third outlet port 182E, afourth outlet port 182F, a plurality of exhaust ports 182G, and acontrol port 182H. The first inlet port 182A is in communication withthe intermediate line 190. The second inlet port 182B is incommunication with the intermediate line 188. The first outlet port 182Cis in communication with a synchronizer supply line 192. The secondoutlet port 182D is in communication with a synchronizer supply line194. The third outlet port 182E is in communication with a synchronizersupply line 196. The fourth outlet port 182F is in communication with asynchronizer supply line 198. The exhaust ports 182G are incommunication with the sump 104. The control port 182H is incommunication with a control line 200 that communicates with the controldevice 174.

The first valve assembly 182 further includes a valve 202 slidablydisposed within a bore 204. The valve 202 is movable between at leasttwo positions by a biasing member 206 and the valve control device 174.The biasing member 206 is preferably a spring and acts on an end of thevalve 202 to bias the valve 202 to the first position or de-strokedposition. The valve control device 174 is preferably an on-off solenoidthat is normally closed. However, it should be appreciated that othertypes of solenoids and other control devices may be employed withoutdeparting from the scope of the present invention. For example, thevalve control device 174 may be a direct acting solenoid. The valvecontrol device 174 includes an inlet port 174A in fluid communicationwith the control device feed line 173 and an outlet port 174B in fluidcommunication with the control line 200. The valve control device 174 iselectrically actuated by the controller 32 between a closed state and anopen state. In the closed state, the inlet port 174A is prevented fromcommunicating with the outlet port 174B. In the open state, the inletport 174A is allowed to communicate with the outlet port 174B.Accordingly, the valve control device 174, when energized to the openstate, allows hydraulic fluid 102 to communicate from the inlet port174A to the outlet port 174B and from the outlet port 174B to thecontrol port 182H via the control line 200. Then, the hydraulic fluid102 acts on an end of the valve 202 to move the valve 202 to the secondposition or stroked position against the bias of the basing member 206.When the valve control device 174 is de-energized or in the closedstate, the flow of hydraulic fluid 102 acting against the valve 202 iscut off and the biasing member 206 moves the valve 202 to the de-strokedposition.

When the valve 202 is in the de-stroked position, the first inlet port182A is in communication with the second outlet port 182D, the secondinlet port 182B is in communication with the fourth outlet port 182F,and the first and third outlet ports 182C, 182E are in communicationwith the exhaust ports 182G. When the valve 202 is in the strokedposition, as shown in FIG. 2B, the first inlet port 182A is incommunication with the first outlet port 182C, the second inlet port182B is in communication with the third outlet port 182E, and the secondand fourth outlet ports 182D, 182F are in communication with the exhaustports 182G. Accordingly, when the valve control device 174 is opened,pressurized hydraulic fluid 102 flows from the first pressure controldevice 140 and a variable flow of hydraulic fluid 102 flows from thefirst flow control device 178 to the second synchronizer actuator 186B.When the valve control device 174 is closed, pressurized hydraulic fluid102 flows from the first pressure control device 140 and a variable flowof hydraulic fluid 102 flows from the first flow control device 178 tothe first synchronizer actuator 186A.

The second actuator pressure control device 141 is preferably anelectrically controlled variable force solenoid having an internalclosed loop pressure control. Various makes, types, and models ofsolenoids may be employed with the present invention so long as thesecond actuator pressure control device 141 is operable to control thepressure of the hydraulic fluid 102. The second actuator pressurecontrol device 141 includes an inlet port 141A that communicates with anoutlet port 141B when the second actuator pressure control device 141 isactivated or energized and includes an exhaust port 141C thatcommunicates with the outlet port 141B when the second actuator pressurecontrol device 141 is inactive or de-energized. Variable activation ofthe second actuator pressure control device 141 regulates or controlsthe pressure of the hydraulic fluid 102 as the hydraulic fluid 102communicates from the inlet port 141A to the outlet port 141B. Theinternal closed loop pressure control provides pressure feedback withinthe solenoid to adjust the amount of flow to the outlet port 141 B basedon a particular current command from the controller 32, therebycontrolling pressure. The inlet port 141A is in communication with themain supply line 126. The outlet port 141B is in communication with anintermediate line 210. The exhaust port 141C is in communication withthe sump 104.

The intermediate line 210 communicates pressurized hydraulic fluid 102from the second actuator pressure control device 141 to the second flowcontrol device 180 and the second valve assembly 184. The second flowcontrol device 180 is preferably an electrically controlled variableforce solenoid. Various makes, types, and models of solenoids may beemployed with the present invention so long as the second flow controldevice 180 is operable to control the flow of the hydraulic fluid 102.The second flow control device 180 includes an inlet port 180A thatcommunicates through an adjustable hydraulic orifice or restriction withan outlet port 180B when the second flow control device 180 is activatedor energized and includes an exhaust port 180C that communicates withthe outlet port 180B when the second flow control device 180 is inactiveor de-energized. Variable activation of the second flow control device180 regulates or controls the flow of the hydraulic fluid 102 as thehydraulic fluid 102 communicates from the inlet port 180A to the outletport 180B. The inlet port 180A is in communication with the intermediateline 210. The outlet port 180B is in communication with an intermediateline 212 which communicates with the second valve assembly 184. Theexhaust port 180C is in communication with the sump 104.

The second valve assembly 184 is operable to selectively direct thepressurized hydraulic fluid 102 flows from the second pressure controldevice 141 and the second actuator flow control device 180 to the thirdsynchronizer actuator 186C and to the fourth synchronizer actuator 186D,as will be described in greater detail below. The second valve assembly184 includes a first inlet port 184A, a second inlet port 184B, a firstoutlet port 184C, a second outlet port 184D, a third outlet port 184E, afourth outlet port 184F, a plurality of exhaust ports 184G, and acontrol port 184H. The first inlet port 184A is in communication withthe intermediate line 212. The second inlet port 184B is incommunication with the intermediate line 210. The first outlet port 184Cis in communication with a synchronizer supply line 214. The secondoutlet port 184D is in communication with a synchronizer supply line216. The third outlet port 184E is in communication with a synchronizersupply line 218. The fourth outlet port 184F is in communication with asynchronizer supply line 220. The exhaust ports 184G are incommunication with the sump 104. The control port 184H is incommunication with the control line 200 that communicates with thecontrol device 174.

The second valve assembly 184 further includes a valve 222 slidablydisposed within a bore 224. The valve 222 is movable between at leasttwo positions by a biasing member 226 and the valve control device 174.The biasing member 226 is preferably a spring and acts on an end of thevalve 222 to bias the valve 222 to the first position or de-strokedposition. The valve control device 174 when energized to the open stateallows hydraulic fluid 102 to communicate from the inlet port 174A tothe outlet port 174B and from the outlet port 174B to the control port184H via the control line 200. Then, the hydraulic fluid 102 acts on anend of the valve 222 to move the valve 222 to the second position orstroked position against the bias of the basing member 226. When thevalve control device 174 is de-energized or in the closed state, theflow of hydraulic fluid 102 acting against the valve 222 is cut off andthe biasing member 226 moves the valve 222 to the de-stroked position.It should be appreciated that the valve control device 174 actuates bothvalve assemblies 182 and 184 when in the open condition via the controlline 200.

When the valve 222 is in the de-stroked position, the first inlet port184A is in communication with the second outlet port 184D, the secondinlet port 184B is in communication with the fourth outlet port 184F,and the first and third outlet ports 184C, 184E are in communicationwith the exhaust ports 184G. When the valve 222 is in the strokedposition, as shown in FIG. 2B, the first inlet port 184A is incommunication with the first outlet port 184C, the second inlet port184B is in communication with the third outlet port 184E, and the secondand fourth outlet ports 184D, 184F are in communication with the exhaustports 184G. Accordingly, when the valve control device 174 is opened,pressurized hydraulic fluid 102 flows from the second pressure controldevice 141 and a variable flow of hydraulic fluid 102 flows from thesecond flow control device 180 to the fourth synchronizer actuator 186D.When the valve control device 174 is closed, pressurized hydraulic fluid102 flows from the second pressure control device 141 and a variableflow of hydraulic fluid 102 flows from the second flow control device180 to the third synchronizer actuator 186C.

The synchronizer actuators 186A-D are preferably two-area pistonassemblies operable to each engage or actuate a shift rail in asynchronizer assembly, but can be three-area piston assemblies withoutdeparting from the scope of the present invention. For example, thefirst synchronizer actuator 186A is operable to actuate the firstsynchronizer assembly 30A, the second synchronizer actuator 186B isoperable to actuate the second synchronizer assembly 30B, the thirdsynchronizer actuator 186C is operable to actuate the third synchronizerassembly 30C, and the fourth synchronizer actuator 186D is operable toactuate the fourth synchronizer assembly 30D.

The first synchronizer actuator 186A includes a piston 230A slidablydisposed within a piston housing or cylinder 232A. The piston 230Apresents two separate areas for pressurized hydraulic fluid to act upon.The piston 230A engages or contacts a finger lever, shift fork, or othershift rail component 233A of the first synchronizer assembly 30A. Thefirst synchronizer actuator 186A includes a fluid port 234A thatcommunicates with a first end 235A of the piston 230A and a fluid port236A that communicates with an opposite second end 237A of the piston230A having a smaller contact area than the first end 235A. Fluid port234A is in communication with the synchronizer supply line 194 and fluidport 236A is in communication with the synchronizer supply line 198.Accordingly, the pressurized hydraulic fluid 102 communicated from thefirst actuator pressure control device 140 enters the first synchronizeractuator 186A through the fluid port 236A and contacts the second end237A of the piston 230A and the flow of hydraulic fluid 102 from thefirst flow control device 178 enters the first synchronizer actuator186A through the fluid port 234A and contacts the first end 235A of thepiston 230A. The difference in force between the hydraulic fluid 102delivered to fluid port 236A from the first actuator pressure controldevice 140 and the hydraulic fluid 102 delivered to fluid port 234A fromthe first flow control device 178 moves the piston 230A between variouspositions. By controlling the flow of hydraulic fluid 102 from the firstflow control device 178, the piston 234A is actuated between the variouspositions. Each position in turn corresponds to a position of the shiftrail of the first synchronizer assembly 30A (i.e., engaged left, engagedright, and neutral). A fork position sensor 240A may be included tocommunicate to the controller 32 the position of the shift fork 233A.

The second synchronizer actuator 186B includes a piston 230B slidablydisposed within a piston housing or cylinder 232B. The piston 230Bpresents two separate areas for pressurized hydraulic fluid to act upon.The piston 230B engages or contacts a finger lever, shift fork, or othershift rail component 233B of the second synchronizer assembly 30B. Thesecond synchronizer actuator 186B includes a fluid port 234B thatcommunicates with a first end 235B of the piston 230B and a fluid port236B that communicates with an opposite second end 237B of the piston230B having a smaller contact area than the first end 235B. Fluid port234B is in communication with the synchronizer supply line 192 and fluidport 236B is in communication with the synchronizer supply line 196.Accordingly, the pressurized hydraulic fluid 102 communicated from thefirst actuator pressure control device 140 enters the secondsynchronizer actuator 186B through the fluid port 236B and contacts thesecond end 237B of the piston 230B and the flow of hydraulic fluid 102from the first flow control device 178 enters the second synchronizeractuator 186B through the fluid port 234B and contacts the first end235B of the piston 230B. The difference in force between the hydraulicfluid 102 delivered to fluid port 236B from the first actuator pressurecontrol device 140 and the hydraulic fluid 102 delivered to fluid port234B from the first flow control device 178 moves the piston 230Bbetween various positions. By controlling the flow of hydraulic fluid102 from the first flow control device 178, the piston 234B is actuatedbetween the various positions. Each position in turn corresponds to aposition of the shift rail of the second synchronizer assembly 30B(i.e., engaged left, engaged right, and neutral). A fork position sensor240B may be included to communicate to the controller 32 the position ofthe shift fork 233B.

The third synchronizer actuator 186C includes a piston 230C slidablydisposed within a piston housing or cylinder 232C. The piston 230Cpresents two separate areas for pressurized hydraulic fluid to act upon.The piston 230C engages or contacts a finger lever, shift fork, or othershift rail component 233C of the third synchronizer assembly 30C. Thethird synchronizer actuator 186C includes a fluid port 234C thatcommunicates with a first end 235C of the piston 230C and a fluid port236C that communicates with an opposite second end 237C of the piston230C having a smaller contact area than the first end 235C. Fluid port234C is in communication with the synchronizer supply line 216 and fluidport 236C is in communication with the synchronizer supply line 220.Accordingly, the pressurized hydraulic fluid 102 communicated from thesecond actuator pressure control device 141 enters the thirdsynchronizer actuator 186C through the fluid port 236C and contacts thesecond end 237C of the piston 230C and the flow of hydraulic fluid 102from the second flow control device 180 enters the third synchronizeractuator 186C through the fluid port 234C and contacts the first end235C of the piston 230C. The difference in force between the hydraulicfluid 102 delivered to fluid port 236C from the second actuator pressurecontrol device 141 and the hydraulic fluid 102 delivered to fluid port234C from the second flow control device 180 moves the piston 230Cbetween various positions. By controlling the flow of hydraulic fluid102 from the second flow control device 180, the piston 234C is actuatedbetween the various positions. Each position in turn corresponds to aposition of the shift rail of the third synchronizer assembly 30C (i.e.,engaged left, engaged right, and neutral). A fork position sensor 240Cmay be included to communicate to the controller 32 the position of theshift fork 233C.

The fourth synchronizer actuator 186D includes a piston 230D slidablydisposed within a piston housing or cylinder 232D. The piston 230Dpresents two separate areas for pressurized hydraulic fluid to act upon.The piston 230D engages or contacts a finger lever, shift fork, or othershift rail component 233D of the fourth synchronizer assembly 30D. Thefourth synchronizer actuator 186D includes a fluid port 234D thatcommunicates with a first end 235D of the piston 230D and a fluid port236D that communicates with an opposite second end 237D of the piston230D having a smaller contact area than the first end 235D. Fluid port234D is in communication with the synchronizer supply line 214 and fluidport 236D is in communication with the synchronizer supply line 218.Accordingly, the pressurized hydraulic fluid 102 communicated from thesecond actuator pressure control device 141 enters the fourthsynchronizer actuator 186D through the fluid port 236D and contacts thesecond end 237D of the piston 230D and the flow of hydraulic fluid 102from the second flow control device 180 enters the fourth synchronizeractuator 186D through the fluid port 234D and contacts the first end235D of the piston 230D. The difference in force between the hydraulicfluid 102 delivered to fluid port 236D from the second actuator pressurecontrol device 141 and the hydraulic fluid 102 delivered to fluid port234D from the second flow control device 180 moves the piston 230Dbetween various positions. By controlling the flow of hydraulic fluid102 from the second flow control device 180, the piston 234A is actuatedbetween the various positions. Each position in turn corresponds to aposition of the shift rail of the fourth synchronizer assembly 30D(i.e., engaged left, engaged right, and neutral). A fork position sensor240D may be included to communicate to the controller 32 the position ofthe shift fork 233D.

*During general operation of the hydraulic control system 100, theaccumulator 130 provides the pressurized hydraulic fluid 102 throughoutthe system and the pump 106 is employed to charge the accumulator 130.Selection of a particular forward or reverse gear ratio is achieved byfirst selectively actuating one of the synchronizer assemblies 30A-D andthen selectively actuating one of the torque transmitting devices 22,24. It should be appreciated that which actuator assembly 30A-D andwhich torque transmitting device 22, 24 provide which forward or reversegear ratio may vary without departing from the scope of the presentinvention.

Generally, the first actuator pressure control device 140 providespressurized hydraulic fluid 102 to each of the synchronizer actuators186A-B and the first flow control device 178 and the second actuatorpressure control device 141 provides pressurized hydraulic fluid 102 toeach of the synchronizer actuators 186C-D and the second flow controldevice 180. Individual synchronizer actuators 186A-D are actuated bycontrolling a flow from one of the flow control devices 178 and 180based upon positioning of the first and second valve assemblies 182 and184.

For example, to actuate the first synchronizer assembly 30A, the firstpressure control device 140 is energized and the valve control device174 is opened to move the first valve assembly 182 to the strokedposition. The first pressure control device 140 provides a steadypressure on the piston 230A and provides a flow of pressurized hydraulicfluid 102 to the first flow control device 178. Bi-directionaltranslation of the first synchronizer assembly 30A is then achieved byselectively energizing the first flow control device 178. For example,energizing the first flow control device 178 to provide a flow ofhydraulic fluid 102 to the synchronizer actuator 186A which provides apressure acting on the piston 230A that is sufficient to overcome thepressure acting on the piston 230A from the first actuator pressurecontrol device 140 moves the piston 230A to a first engaged position.Energizing the first flow control device 178 to provide a flow ofhydraulic fluid 102 to the synchronizer actuator 186A which provides apressure acting on the piston 230A that is balanced with the pressureacting on the piston 230A from the first actuator pressure controldevice 140 moves the piston 230A to a neutral or unengaged position.Energizing or de-energizing the first flow control device 178 to providea flow of hydraulic fluid 102 to the synchronizer actuator 186A whichprovides a pressure acting on the piston 230A that is insufficient toovercome the pressure acting on the piston 230A from the first actuatorpressure control device 140 moves the piston 230A to a second engagedposition.

To actuate the second synchronizer assembly 30B, the first pressurecontrol device 140 is energized and the valve control device 174 isclosed to move the first valve assembly 182 to the de-stroked position.The first pressure control device 140 provides a steady pressure on thepiston 230B and provides a flow of pressurized hydraulic fluid 102 tothe first flow control device 178. Bi-directional translation of thesecond synchronizer assembly 30B is then achieved by selectivelyenergizing the first flow control device 178. For example, energizingthe first flow control device 178 to provide a flow of hydraulic fluid102 to the synchronizer actuator 186B which provides a pressure actingon the piston 230B that is sufficient to overcome the pressure acting onthe piston 230B from the first actuator pressure control device 140moves the piston 230B to a first engaged position. Energizing the firstflow control device 178 to provide a flow of hydraulic fluid 102 to thesynchronizer actuator 186B which provides a pressure acting on thepiston 230B that is balanced with the pressure acting on the piston 230Bfrom the first actuator pressure control device 140 moves the piston230B to a neutral or unengaged position. Energizing or de-energizing thefirst flow control device 178 to provide a flow of hydraulic fluid 102to the synchronizer actuator 186B which provides a pressure acting onthe piston 230B that is insufficient to overcome the pressure acting onthe piston 230B from the first actuator pressure control device 140moves the piston 230B to a second engaged position.

To actuate the third synchronizer assembly 30C, the second pressurecontrol device 141 is energized and the valve control device 174 isclosed to move the second valve assembly 184 to the de-stroked position.The second pressure control device 141 provides a steady pressure on thepiston 230C and provides a flow of pressurized hydraulic fluid 102 tothe second flow control device 180. Bi-directional translation of thethird synchronizer assembly 30C is then achieved by selectivelyenergizing the second flow control device 180. For example, energizingthe second flow control device 180 to provide a flow of hydraulic fluid102 to the synchronizer actuator 186C which provides a pressure actingon the piston 230C that is sufficient to overcome the pressure acting onthe piston 230C from the second actuator pressure control device 141moves the piston 230C to a first engaged position. Energizing the secondflow control device 180 to provide a flow of hydraulic fluid 102 to thesynchronizer actuator 186C which provides a pressure acting on thepiston 230C that is balanced with the pressure acting on the piston 230Cfrom the second actuator pressure control device 141 moves the piston230C to a neutral or unengaged position. Energizing or de-energizing thesecond flow control device 180 to provide a flow of hydraulic fluid 102to the synchronizer actuator 186C which provides a pressure acting onthe piston 230C that is insufficient to overcome the pressure acting onthe piston 230C from the second actuator pressure control device 141moves the piston 230C to a second engaged position.

To actuate the fourth synchronizer assembly 30D, the second pressurecontrol device 141 is energized and the valve control device 174 isopened to move the second valve assembly 184 to the stroked position.The second pressure control device 141 provides a steady pressure on thepiston 230D and provides a flow of pressurized hydraulic fluid 102 tothe second flow control device 180. Bi-directional translation of thethird synchronizer assembly 30D is then achieved by selectivelyenergizing the second flow control device 180. For example, energizingthe second flow control device 180 to provide a flow of hydraulic fluid102 to the synchronizer actuator 186D which provides a pressure actingon the piston 230D that is sufficient to overcome the pressure acting onthe piston 230D from the second actuator pressure control device 141moves the piston 230D to a first engaged position. Energizing the secondflow control device 180 to provide a flow of hydraulic fluid 102 to thesynchronizer actuator 186D which provides a pressure acting on thepiston 230D that is balanced with the pressure acting on the piston 230Dfrom the second actuator pressure control device 141 moves the piston230D to a neutral or unengaged position. Energizing or de-energizing thesecond flow control device 180 to provide a flow of hydraulic fluid 102to the synchronizer actuator 186D which provides a pressure acting onthe piston 230D that is insufficient to overcome the pressure acting onthe piston 230D from the second actuator pressure control device 141moves the piston 230D to a second engaged position.

To engage or actuate the first torque transmitting device 22, the firstclutch pressure control device 136 and the first clutch flow controldevice 144 are energized or opened. To engage or actuate the secondtorque transmitting device 24, the second clutch pressure control device138 and the second clutch flow control device 160 are energized oropened.

By providing flow control of the clutches 22 and 24 and/or thesynchronizer assemblies 30A-D, the hydraulic control system 100 isoperable to provide direct clutch position control, direct synchronizeractuator position control, and variable clutch and synchronizer actuatorposition control. At the same time, quick clutch response times areenabled, spin losses are reduced, and packaging space of the hydrauliccontrol system 100 is reduced, all of which contributes to improved fueleconomy and performance. The hydraulic control system 100 is alsocompatible with BAS/BAS+ hybrid systems. Finally, failure modeprotection is enabled through pre-staged position control of the controldevices 136, 138, 140, 141, 144, 160, 178, 180, and the valves 182 and184.

The description of the invention is merely exemplary in nature andvariations that do not depart from the general essence of the inventionare intended to be within the scope of the invention. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention.

1. A hydraulic control system for controlling a dual clutchtransmission, the hydraulic control system comprising: a source ofpressurized hydraulic fluid; a first, a second, a third and a fourthpressure control solenoid in downstream fluid communication with thesource of pressurized hydraulic fluid; a first flow control solenoid indownstream fluid communication with the first pressure control solenoid;a second flow control solenoid in downstream fluid communication withthe second pressure control solenoid; a first clutch actuator indownstream fluid communication with the first flow control solenoid forselectively actuating a first clutch of the dual clutch transmission; asecond clutch actuator in downstream fluid communication with the secondflow control solenoid for selectively actuating a second clutch of thedual clutch transmission; a third flow control solenoid in downstreamfluid communication with the third pressure control solenoid; a fourthflow control solenoid in downstream fluid communication with the fourthpressure control solenoid; a first logic valve assembly in downstreamfluid communication with the third flow control solenoid and the thirdpressure control solenoid, wherein the first logic control valveassembly has a valve movable between a first and a second position; asecond logic valve assembly in downstream fluid communication with thefourth flow control solenoid and the fourth pressure control solenoid,wherein the second logic control valve assembly has a valve movablebetween a first and a second position; a first actuator in downstreamfluid communication with the first logic valve assembly, wherein thefirst actuator is movable between a first and second position when thevalve of the first logic control valve assembly is in the firstposition; a second actuator in downstream fluid communication with thefirst logic valve assembly, wherein the second actuator is movablebetween a first and second position when the valve of the first logiccontrol valve assembly is in the second position; a third actuator indownstream fluid communication with the second logic valve assembly,wherein the third actuator is movable between a first and secondposition when the valve of the second logic control valve assembly is inthe first position; and a fourth actuator in downstream fluidcommunication with the second logic valve assembly, wherein the fourthactuator is movable between a first and second position when the valveof the second logic control valve assembly is in the second position,and wherein the third flow control solenoid generates a first flow ofhydraulic fluid to move at least one of the first and second actuatorsinto the first position and the third pressure control solenoidgenerates a first hydraulic fluid pressure to move at least one of thefirst and second actuators into the second position and wherein thefourth flow control solenoid generates a second flow of hydraulic fluidto move at least one of the third and fourth actuators into the firstposition and the fourth pressure control solenoid generates a secondhydraulic fluid pressure to move at least one of the third and fourthactuators into the second position.
 2. The hydraulic control system ofclaim 1 further comprising a logic valve control solenoid in downstreamfluid communication with the first and second pressure control solenoidsand in upstream fluid communication with the first and second logicvalve assemblies.
 3. The hydraulic control system of claim 1 wherein thelogic valve control solenoid is configured to communicate a thirdpressurized hydraulic fluid from at least one of the first and secondpressure control solenoids to the first and second logic valveassemblies in order to move each of the valves of the first and secondlogic valve assemblies to the second positions.
 4. The hydraulic controlsystem of claim 3 further comprising a three way check ball valvedisposed in downstream fluid communication with the first pressurecontrol solenoid and the second pressure control solenoid and inupstream fluid communication with the logic valve control solenoid.
 5. Ahydraulic control system for controlling a dual clutch transmission anda plurality of synchronizers in a transmission, the hydraulic controlsystem comprising: a source of pressurized hydraulic fluid; a first, asecond, a third and a fourth pressure control solenoid each having aninlet port in downstream fluid communication with the source ofpressurized hydraulic fluid and each having an outlet port; a first flowcontrol solenoid having an inlet port in downstream fluid communicationwith the outlet port of the first pressure control solenoid and havingan outlet port; a second flow control solenoid having an inlet port indownstream fluid communication with the outlet port of the secondpressure control solenoid and having an outlet port; a first clutchactuator in downstream fluid communication with the outlet port of thefirst flow control solenoid, the first clutch actuator configured toselectively actuate a first clutch of the dual clutch transmission; asecond clutch actuator in downstream fluid communication with the outletport of the second flow control solenoid, the second clutch actuatorconfigured to selectively actuate a second clutch of the dual clutchtransmission; a third flow control solenoid having an inlet port indownstream fluid communication with the outlet port of the thirdpressure control solenoid and having an outlet port; a fourth flowcontrol solenoid having an inlet port in downstream fluid communicationwith the outlet port of the fourth pressure control solenoid and havingan outlet port; a first logic valve assembly in downstream fluidcommunication with the outlet port of the third flow control solenoidand the outlet port of the third pressure control solenoid, wherein thefirst logic control valve assembly has a valve movable between a firstand a second position; a second logic valve assembly in downstream fluidcommunication with the outlet port of the fourth flow control solenoidand the outlet port of the fourth pressure control solenoid, wherein thesecond logic control valve assembly has a valve movable between a firstand a second position; a first actuator in downstream fluidcommunication with the first logic valve assembly, wherein the firstactuator is movable between a first and second position when the valveof the first logic control valve assembly is in the first position; asecond actuator in downstream fluid communication with the first logicvalve assembly, wherein the second actuator is movable between a firstand second position when the valve of the first logic control valveassembly is in the second position; a third actuator in downstream fluidcommunication with the second logic valve assembly, wherein the thirdactuator is movable between a first and second position when the valveof the second logic control valve assembly is in the first position; anda fourth actuator in downstream fluid communication with the secondlogic valve assembly, wherein the fourth actuator is movable between afirst and second position when the valve of the second logic controlvalve assembly is in the second position, wherein the third flow controlsolenoid generates a first flow of hydraulic fluid to move at least oneof the first and second actuators into the first position and the thirdpressure control solenoid generates a first hydraulic fluid pressure tomove at least one of the first and second actuators into the secondposition and wherein the fourth flow control solenoid generates a secondflow of hydraulic fluid to move at least one of the third and fourthactuators into the first position and the fourth pressure controlsolenoid generates a second hydraulic fluid pressure to move at leastone of the third and fourth actuators into the second position, andwherein each of the first, second, third, and fourth actuators isconfigured to position a synchronizer between at least an engagedposition and a neutral position and wherein the first and secondpositions of each of the first, second, third, and fourth actuatorscorresponds to one of the neutral and engaged positions of thesynchronizer.
 6. The hydraulic control system of claim 5 furthercomprising a logic valve control solenoid in downstream fluidcommunication with the outlet ports of the first and second pressurecontrol solenoids and in upstream fluid communication with the first andsecond logic valve assemblies.
 7. The hydraulic control system of claim6 wherein the logic valve control solenoid is configured to communicatea third pressurized hydraulic fluid from at least one of the first andsecond pressure control solenoids to the first and second logic valveassemblies in order to move each of the valves of the first and secondlogic valve assemblies to the second positions.
 8. The hydraulic controlsystem of claim 7 further comprising a three way check ball valve havinga first inlet port in downstream fluid communication with the outletport of the first pressure control solenoid, a second inlet port indownstream fluid communication with the outlet port of the secondpressure control solenoid, and an outlet port in upstream fluidcommunication with the logic valve control solenoid.
 9. The hydrauliccontrol system of claim 5 wherein the first, second, third, and fourthactuators are moved between their first and second positions by movingthe valve of the first and second logic valve assemblies and varying thefirst and second flows of hydraulic fluid to either overcome or notovercome a constant force generated by each of the first and secondpressurized hydraulic fluids acting on each of the first, second, third,and fourth actuators.
 10. The hydraulic control system of claim 5wherein the source of pressurized hydraulic fluid includes a pump and anaccumulator.
 11. A hydraulic control system for controlling a dualclutch transmission and a plurality of synchronizers in a transmission,the hydraulic control system comprising: a source of pressurizedhydraulic fluid; a first, a second, a third and a fourth pressurecontrol solenoid each having an inlet port in downstream fluidcommunication with the source of pressurized hydraulic fluid and eachhaving an outlet port; a first flow control solenoid having an inletport in downstream fluid communication with the outlet port of the firstpressure control solenoid and having an outlet port; a second flowcontrol solenoid having an inlet port in downstream fluid communicationwith the outlet port of the second pressure control solenoid and havingan outlet port; a first clutch actuator in downstream fluidcommunication with the outlet port of the first flow control solenoid,the first clutch actuator configured to selectively actuate a firstclutch of the dual clutch transmission; a second clutch actuator indownstream fluid communication with the outlet port of the second flowcontrol solenoid, the second clutch actuator configured to selectivelyactuate a second clutch of the dual clutch transmission; a third flowcontrol solenoid having an inlet port in downstream fluid communicationwith the outlet port of the third pressure control solenoid and havingan outlet port; a fourth flow control solenoid having an inlet port indownstream fluid communication with the outlet port of the fourthpressure control solenoid and having an outlet port; a first logic valveassembly in downstream fluid communication with the outlet port of thethird flow control solenoid and the outlet port of the third pressurecontrol solenoid, wherein the first logic control valve assembly has avalve movable between a first and a second position; a second logicvalve assembly in downstream fluid communication with the outlet port ofthe fourth flow control solenoid and the outlet port of the fourthpressure control solenoid, wherein the second logic control valveassembly has a valve movable between a first and a second position; alogic valve control solenoid in upstream fluid communication with thefirst and second logic valve assemblies; a three way check ball valvehaving a first inlet port in downstream fluid communication with theoutlet port of the first pressure control solenoid, a second inlet portin downstream fluid communication with the outlet port of the secondpressure control solenoid, and an outlet port in upstream fluidcommunication with the logic valve control solenoid; a first actuator indownstream fluid communication with the first logic valve assembly,wherein the first actuator is movable between a first and secondposition when the valve of the first logic control valve assembly is inthe first position; a second actuator in downstream fluid communicationwith the first logic valve assembly, wherein the second actuator ismovable between a first and second position when the valve of the firstlogic control valve assembly is in the second position; a third actuatorin downstream fluid communication with the second logic valve assembly,wherein the third actuator is movable between a first and secondposition when the valve of the second logic control valve assembly is inthe first position; and a fourth actuator in downstream fluidcommunication with the second logic valve assembly, wherein the fourthactuator is movable between a first and second position when the valveof the second logic control valve assembly is in the second position,wherein the third flow control solenoid generates a first flow ofhydraulic fluid to move at least one of the first and second actuatorsinto the first position and the third pressure control solenoidgenerates a first hydraulic fluid pressure to move at least one of thefirst and second actuators into the second position and wherein thefourth flow control solenoid generates a second flow of hydraulic fluidto move at least one of the third and fourth actuators into the firstposition and the fourth pressure control solenoid generates a secondhydraulic fluid pressure to move at least one of the third and fourthactuators into the second position, wherein the logic valve controlsolenoid is configured to communicate a third pressurized hydraulicfluid from at least one of the first and second pressure controlsolenoids to the first and second logic valve assemblies in order tomove each of the valves of the first and second logic valve assembliesto the second positions, and wherein each of the first, second, third,and fourth actuators is configured to position a synchronizer between atleast an engaged position and a neutral position and wherein the firstand second positions of each of the first, second, third, and fourthactuators corresponds to one of the neutral and engaged positions of thesynchronizer.
 12. The hydraulic control system of claim 11 wherein thefirst, second, third, and fourth actuators are moved between their firstand second positions by moving the valve of the first and second logicvalve assemblies and varying the first and second flows of hydraulicfluid to either overcome or not overcome a constant force generated byeach of the first and second pressurized hydraulic fluids acting on eachof the first, second, third, and fourth actuators.
 13. The hydrauliccontrol system of claim 11 wherein the source of pressurized hydraulicfluid includes a pump and an accumulator.